#box1 {
    width: 100px;
    height: 100px;
    background-image: url(./pic1.png);
    background-repeat: no-repeat;
    background-size: 100% 100%;
}
#box2 {
    width: 100px;
    height: 100px;
    background-image: url(./pic2.png);
    background-repeat: no-repeat;
    background-size: 100% 100%;
}
#box3 {
    width: 100px;
    height: 100px;
    background-image: url(./pic3.png);
    background-repeat: no-repeat;
    background-size: 100% 100%;
}